/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.io;

import java.io.IOException;

/**
 * This DataEntryReader delegates to one of two other DataEntryReader instances, depending on whether the data entry
 * passes through a given data entry filter or not.
 *
 * @author Eric Lafortune
 */
public class FilteredDataEntryReader implements DataEntryReader {
    private final DataEntryFilter dataEntryFilter;
    private final DataEntryReader acceptedDataEntryReader;
    private final DataEntryReader rejectedDataEntryReader;

    /**
     * Creates a new FilteredDataEntryReader with only a reader for accepted data entries.
     * 
     * @param dataEntryFilter the data entry filter.
     * @param acceptedDataEntryReader the DataEntryReader to which the reading will be delegated if the filter accepts
     *        the data entry. May be <code>null</code>.
     */
    public FilteredDataEntryReader(DataEntryFilter dataEntryFilter, DataEntryReader acceptedDataEntryReader) {
        this(dataEntryFilter, acceptedDataEntryReader, null);
    }

    /**
     * Creates a new FilteredDataEntryReader.
     * 
     * @param dataEntryFilter the data entry filter.
     * @param acceptedDataEntryReader the DataEntryReader to which the reading will be delegated if the filter accepts
     *        the data entry. May be <code>null</code>.
     * @param rejectedDataEntryReader the DataEntryReader to which the reading will be delegated if the filter does not
     *        accept the data entry. May be <code>null</code>.
     */
    public FilteredDataEntryReader(DataEntryFilter dataEntryFilter, DataEntryReader acceptedDataEntryReader,
        DataEntryReader rejectedDataEntryReader) {
        this.dataEntryFilter = dataEntryFilter;
        this.acceptedDataEntryReader = acceptedDataEntryReader;
        this.rejectedDataEntryReader = rejectedDataEntryReader;
    }

    // Implementations for DataEntryReader.

    public void read(DataEntry dataEntry) throws IOException {
        DataEntryReader dataEntryReader =
            dataEntryFilter.accepts(dataEntry) ? acceptedDataEntryReader : rejectedDataEntryReader;

        if (dataEntryReader != null) {
            dataEntryReader.read(dataEntry);
        }
    }
}
